The invention relates to a wheel with a variable diameter comprising plates guided in two mutually opposed disks and displaceable from the inside toward the outside and, respectively, from the outside toward the inside.
DE-A1-31 37 018 discloses a wheel having an adjustable diameter. In this wheel, segments are arranged between two disks having a fixed mutual spacing; these segments can be displaced by way of a gear mechanism in radial slots in the disks. The segments are in contact with each other only in their innermost position so that, in any position with a larger diameter, gaps are formed in the outer surface periphery having a deleterious effect during operation of the wheel.
Additionally, a gear mechanism is required for the radial shifting of the segments.
In the wheel disclosed in US-A-999,530, triangular plates are moved radially and with respect to one another by means of spokes supported on the inside of the triangular plates and guided in a hub on the shaft, and by means of arms likewise connected to the plates with one of their ends and to an adjustable nut with their other ends. It is readily apparent that this arrangement is unable to transmit any relatively high torques.
The pulley drive transmission described in DE-C-493,825 with conical disk components has the drawback of high axial forces.
The invention is based on the object of providing a wheel having a variable diameter which can be utilized for the power-derived or shape-mating power transmission from a load transmitting means, such as belts, chains, or the like, to the periphery of the wheel, or vice versa.
According to the invention, this object has been attained by providing that the two mutually opposed disks can be shifted with respect to each other in the direction of their axis of rotation, that the plates taper from one disk to the other as measured in the peripheral direction, and that the plates, disposed side-by-side, are coupled together in a displaceable fashion.
As compared with conventional wheels with conical disks, cooperating with load transmitting means which urge the disks apart during operation, considerably smaller axial friction or compressive forces occur in the wheel according to this invention.
In order to obtain a maximally large range of variation for the diameter of the wheel, the disks exhibit cutouts for the plates guided in the respectively opposite disk.
In one embodiment of this invention, the plates are coupled along their lateral faces by groove and tongue joints wherein respectively one round, undercut strip on one plate is received in a groove of annular shape in cross section provided in the other plate, or the provision is made that the connection of the plates along their lateral faces is constituted by a guide means wherein an obliquely outwardly projecting extension of one plate engages into a corresponding channel in the other plate in order to achieve maximally high stability of the wheel. These connections can be arranged in the zone of the lateral faces of the plates. However, it is also possible to locate these connections radially within or radially outside of the plates. It is likewise possible to additionally provide springs which stress the plates from the outside toward the inside.
The plates are preferably guided in radial slots of the disks; these slots can also be inclined at an angle with respect to the radial orientation whereby a more advantageous force distribution can result in the wheel. Curved slots are also feasible.
The provision can be made within the scope of this invention that the plates are guided by way of sliding surfaces on a lateral face of the disks and by way of a guide extension in the slots. Thereby, the plates are guided by still additional, enlarged sliding surfaces whereby a higher stability of the guidance of the plates is attained.
If the force transmission between the wheel and the load transmission means is to take place in a shape-mating fashion, then the provision can be made according to this invention that at least respectively one sliding member is arranged on the plates which is displaceable along a sliding path approximately in the direction of the axis of rotation of the wheel, and that this sliding member is displaceable in the peripheral direction against the force of springs or inserts of an elastic material, this sliding member carrying at least one dog. On account of the sliding members provided on the plates which carry entrainment means corresponding to the load transmission means, the latter can always remain in the center of the wheel, even if its diameter and width are changed. This is accomplished by guide means which are preferably in parallel to the axis of rotation of the wheel; these guide means can also be inclined with respect to the axis of rotation in order to ensure centering of the load transmission means and of the sliding members in the region of the peripheral center line of the wheel.
Since the interspace between the individual sliding members and their dogs does not always correspond to the pitch of the load transmission means when the wheel diameter changes, the sliding members are also displaceable on the plates in the peripheral direction against the force of springs, for example corrugated flat coil springs or strips of rubber or a similarly elastic material, whereby adaptation to the pitch is obtained, on the one hand, and improved distribution of the force transmission takes place, on the other hand, from the load transmission means to all sliding members in engagement therewith and furthermore via the springs to the plates.
By combining two wheels according to this invention and a load transmission means, an infinitely variable transmission is obtained.